Mercurial > hg > nginx
view src/os/unix/ngx_errno.c @ 7784:8cc5b0365ee5
Improved maximum errno detection.
Previously, systems without sys_nerr (or _sys_nerr) were handled with an
assumption that errors start at 0 and continuous. This is, however, not
something POSIX requires, and not true on some platforms.
Notably, on Linux, where sys_nerr is no longer available for newly linked
binaries starting with glibc 2.32, there are gaps in error list, which
used to stop us from properly detecting maximum errno. Further, on
GNU/Hurd errors start at 0x40000001.
With this change, maximum errno detection is moved to the runtime code,
now able to ignore gaps, and also detects the first error if needed.
This fixes observed "Unknown error" messages as seen on Linux with
glibc 2.32 and on GNU/Hurd.
author | Maxim Dounin <mdounin@mdounin.ru> |
---|---|
date | Mon, 01 Mar 2021 20:00:43 +0300 |
parents | f1a0de6eb505 |
children | c43a2e8fdf7e |
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/* * Copyright (C) Igor Sysoev * Copyright (C) Nginx, Inc. */ #include <ngx_config.h> #include <ngx_core.h> /* * The strerror() messages are copied because: * * 1) strerror() and strerror_r() functions are not Async-Signal-Safe, * therefore, they cannot be used in signal handlers; * * 2) a direct sys_errlist[] array may be used instead of these functions, * but Linux linker warns about its usage: * * warning: `sys_errlist' is deprecated; use `strerror' or `strerror_r' instead * warning: `sys_nerr' is deprecated; use `strerror' or `strerror_r' instead * * causing false bug reports. */ static ngx_str_t *ngx_sys_errlist; static ngx_str_t ngx_unknown_error = ngx_string("Unknown error"); static ngx_err_t ngx_first_error; static ngx_err_t ngx_last_error; u_char * ngx_strerror(ngx_err_t err, u_char *errstr, size_t size) { ngx_str_t *msg; if (err >= ngx_first_error && err < ngx_last_error) { msg = &ngx_sys_errlist[err - ngx_first_error]; } else { msg = &ngx_unknown_error; } size = ngx_min(size, msg->len); return ngx_cpymem(errstr, msg->data, size); } ngx_int_t ngx_strerror_init(void) { char *msg; u_char *p; size_t len; ngx_err_t err; #if (NGX_SYS_NERR) ngx_first_error = 0; ngx_last_error = NGX_SYS_NERR; #elif (EPERM > 1000 && EPERM < 0x7fffffff - 1000) /* * If number of errors is not known, and EPERM error code has large * but reasonable value, guess possible error codes based on the error * messages returned by strerror(), starting from EPERM. Notably, * this covers GNU/Hurd, where errors start at 0x40000001. */ for (err = EPERM; err > EPERM - 1000; err--) { ngx_set_errno(0); msg = strerror(err); if (errno == EINVAL || msg == NULL || strncmp(msg, "Unknown error", 13) == 0) { continue; } ngx_first_error = err; } for (err = EPERM; err < EPERM + 1000; err++) { ngx_set_errno(0); msg = strerror(err); if (errno == EINVAL || msg == NULL || strncmp(msg, "Unknown error", 13) == 0) { continue; } ngx_last_error = err + 1; } #else /* * If number of errors is not known, guess it based on the error * messages returned by strerror(). */ ngx_first_error = 0; for (err = 0; err < 1000; err++) { ngx_set_errno(0); msg = strerror(err); if (errno == EINVAL || msg == NULL || strncmp(msg, "Unknown error", 13) == 0) { continue; } ngx_last_error = err + 1; } #endif /* * ngx_strerror() is not ready to work at this stage, therefore, * malloc() is used and possible errors are logged using strerror(). */ len = (ngx_last_error - ngx_first_error) * sizeof(ngx_str_t); ngx_sys_errlist = malloc(len); if (ngx_sys_errlist == NULL) { goto failed; } for (err = ngx_first_error; err < ngx_last_error; err++) { msg = strerror(err); if (msg == NULL) { ngx_sys_errlist[err - ngx_first_error] = ngx_unknown_error; continue; } len = ngx_strlen(msg); p = malloc(len); if (p == NULL) { goto failed; } ngx_memcpy(p, msg, len); ngx_sys_errlist[err - ngx_first_error].len = len; ngx_sys_errlist[err - ngx_first_error].data = p; } return NGX_OK; failed: err = errno; ngx_log_stderr(0, "malloc(%uz) failed (%d: %s)", len, err, strerror(err)); return NGX_ERROR; }